[unreadable] This proposal is submitted in response to RFA CA-04-03 by a new investigator. It outlines pilot research (R21) to evaluate a physical exercise intervention to improve young childhood cancer survivors' physical fitness and involvement in physical activity. The team of researchers assembled for this study will contribute exceptional expertise in pediatric psycho-oncology, pediatric oncology, pediatric endocrinology and fitness exercise in oncology patients. We hypothesize that the physical exercise program, offered as an intervention to young survivors of childhood cancer, will positively affect their physical and psychological adjustment to their disease and its treatment. Subjects who receive the intervention and health and fitness education will be more likely to experience better physical functioning and more improved quality of life than those enrolled in a control group who receive health and fitness education alone. It is anticipated that the intervention will produce positive changes in several of the long-term morbidities associated with childhood cancer, including physical deconditioning, obesity, fatigue, related metabolic conditions and problems in psychological adjustment. [unreadable] The study utilizes a randomized, between groups, repeated measures design, with an Intervention Condition (IC) and a Control Condition (CC). 40 young survivors of childhood cancer, 5+ years from their diagnosis will be recruited. 20 subjects will be randomly assigned to either the IC or the CC. Subjects assigned to the IC will receive a 12-week long aerobic exercise and physical activity program, coupled with health and fitness education. CC subjects will receive only the health and fitness education. Primary outcomes of physical exercise capacity (VO2max), involvement in physical activity and health-related quality of life will be assessed at baseline, end of therapy, and at 3 months after the end of therapy. A number of secondary outcomes including indices of metablolic function, body mass/composition, and psychological adjustment will also be obtained. Data from this study will be instrumental in development of a more definitive, large-scale study of this important issue. Ultimately, this research will provide vital information regarding the long-term physical sequelae of childhood cancer, and will direct interventions to mitigate these outcomes and enhance quality of life. [unreadable] [unreadable] [unreadable]